Option to set kubeConfigFile

[Slava]

During Manual run inside Kubernetes via Job #7, we used custom app config and specified

                    kubeConfigFile: "/opt/kubeconfig.yaml",

for custom kubeconfig, to access Kubernetes cluster.

And we may consider the following

1. A CLI option or environment variable to set a custom kubeconfig file
2. It may be usefully to specify a context, in case when kubeconfig contains more than one - mostly for local use cases
3. Handle KUBECONFIG as a native variable - Set the KUBECONFIG environment variable

[Slava]

Now we have an environment variable KUBECONFIG in bc4035e.